The present invention relates to a power generating system, and more particularly to an electro-mechanical-hydraulic power generating system.
Various types of power generating systems are known. Frequently, such systems incorporate a prime mover, a transmission system for transmitting power generated by the prime mover, and an output device for delivering the power transmitted by the transmission system to a machine which utilitizes the transmitted power to perform work. A good example of such a power generating system is found in motor vehicles, wherein the prime mover is the vehicle's internal combustion engine, the transmission system includes the vehicle's drive train, and the output device is the vehicle's hub to which wheels are attached for performing work by propelling the vehicle.
The greater the work ultimately to be performed, the more powerful the prime mover must be. Demands for power generating systems capable of handling greater and greater work loads have been met by providing prime movers having progressively greater torque outputs, while the output speed of typical prime movers has not been correspondingly increased. For example, large earth moving machines use massive diesel engines which operate at a few thousand R.P.M., within the same speed operating range as conventional passenger automobile engines. When the prime mover is an internal combustion engine it is not practicable to increase the prime mover's power output by increasing its operating speed. Practical limitations dictate that internal combustion engines not operate, in the usual case, greater than a few thousand R.P.M.
Presently there is a considerable interest in power generating systems, for vehicular use and for other applications, which include an electric motor for a prime mover. However, low-speed high-torque electric motors, suitable for vehicular use and having operating characteristics comparable to internal combustion engines presently used in motor vehicles, are large and expensive. Additionally, electric motors require a source of electricity. When the electric motor is used to power a vehicle the source of electricity must necessarily be provided from a storage device, such as a battery. Battery depletion is a serious limitation on the use of electric motors for performing a large amount of work.
Power transmission systems are made in a wide variety of different designs. Some are purely mechanical, while others are hydraulic or mechanical-hydraulic. Hydraulic power transmission systems have found widespread application when very heavy loads are involved. When the amount of work to be performed is extremely large there may be no practical alternative but to use hydraulic transmission systems. For example, giant earth moving vehicles use hydraulic transmissions for controlling the large amounts of power, at very high torques, generated by their large internal combustion engines.